The traditional process of refining magnesium adopts the Pidgeon method. The method uses a horizontal furnace. The furnace body is laid on the base with refractory bricks. A plurality of reduction tanks are laid and distributed in the furnace. The reduction tank is filled with reactant pellets. Firstly, the reduction tank is heated with radiant heat from a hearth outside of the reduction tank; secondly, the heat is radiated and transmitted to the reactant pellets by the reduction tank; finally, the heat is transmitted by the reactant pellets through a mutual relay method. It is a peripheral heating. It has been proved that: as to the method of heating from a big hearth built by laying refractory bricks, there are a big space in the hearth, big transmitting radius of heat radiation and a blind angle of high-temperature convection flue gas, resulting in low heat transfer rate, large temperature gradient, bad temperature uniformity, and large radius of heat radiation transfer; thus, it costs too much time (10-12 hours) to make feeds in the reduction tank reach the reduction temperature of 1150-1200 DEG C according to technological requirements. The reduction tank is easy to generate thermal creep due to uneven heating, and is scrapped after being used about 2 months. Furthermore, each reduction tank can only accommodate hundreds kilograms of feeds due to its small volume. Consequently, we need to invest on many furnaces and reduction tanks in order to reach the requirements for production capacity. Therefore, the reduction furnace built by laying refractory bricks has the disadvantages of large floor space, low production efficiency, high labor intensity, high energy consumption, low magnesium reduction rate, serious environmental pollution, short service life of the reduction tank, and unavailability for mechanical or automated loading and unloading.